1. Field of the Invention
The present invention relates to raised floor air-grate panels. In particular, it relates to an improved directional flow raised floor air-grate panel, and system for the improved thermal management of computer rooms.
2. Description of the Related Art
Raised floors are used in data centers to create a space between a sub-floor of the building and the normal working environment of the computer room. The space between the sub-floor and the raised floor panels creates an under floor cool-air circulating plenum for thermal management of the data processing servers installed in rack systems on top of the raised floor. The floor panels, themselves, are either solid or perforated. Of the perforated panels, manufacturers have made new design changes in an effort to increase the available open area of the panels, in order to increase the air flow of cooling air throughout the room. These efforts have led to the production and use of air-grate raised floor panels. The air-grate panels use an open frame design so that cooling air, originating in the under floor, or lower, plenum flows upwardly through the openings in the air-grate frame and into the computer room in order to aid in cooling the server cabinets installed on top of the raised floor. The air-grate panels may also include perforated top plates, connected to the air-grate structural frame members, in order to provide a variety of different working surfaces having a desired aesthetic appearance, or with the perforations, or openings, in the plate configured so as comply with certain federal and state regulations, as they relate to occupational safety and/or persons with disabilities, or to increase air flow and cooling efficiency.
Overall, the cooling components, of a computer room, are charged with creating, and moving air on the data center floor. From there, the room itself must maintain separate climates in relation to the cool air, which is required by the servers, and the hot air which they exhaust. Without separate boundaries, the air paths mix, resulting in both economic and ecological consequences. Air-grate panels are thus a key cooling component in the overall design and construction of computer rooms. With a raised floor, the use of air-grate panels is a way to separate the computer room into a “lower-plenum/upper-plenum” air handling boundary configuration where the cooling air “originates” in the lower plenum, flows upwardly through the openings in the air-grate panels, and is made available for cooling the server cabinets, installed on the raised floor, in the upper plenum of the computer room. In operation, the data processors heat the air, in the upper plenum, where it is returned to the computer room air conditioning units (“CRAC”) for cooling, and recycling the conditioned air back into the lower, or under-floor, plenum.
A further refinement, in the use of air-grate floor panels, came in the early 2000s, when scientists advanced the concept of “hot aisle/cold aisle”, as an additional means for attempting to achieve air separation within the server room. This design, which aligns data center cabinets into alternating rows, endures in critical facilities throughout the world, and is widely regarded as the first major step in improving airflow management. In use, part of this air flow, or stream, enters the racks and then the equipment, and part of the air flow bypasses the equipment and returns to the air handling units. The air that enters the servers is heated, and then exhausted through the back of the servers where it is recycled as return air into the air handling units. Typically, some intermixing of the hot and cold air paths is experienced due to improper sealing in the rack, or recirculation above and around the sides of the rack rows.
Other conditions occur which interfere with optimum cooling efficiency, as well. For example, “bypass air” is an interfering condition observed when conditioned air that does not reach computer equipment escapes through cable cut-outs, holes under cabinets, or misplaced perforated tiles or holes in the computer room perimeter walls. Bypass air limits the precise delivery of cold air at the server intake. “Hot air recirculation” is also an interfering condition found under conditions where waste heat enters the cold aisle. In order to combat this condition, operators ensure that the cooling infrastructure must throw colder air at the equipment to offset mixing. Another such condition is hot air contamination which prohibits the air handlers from receiving the warmest possible exhaust air, rendering their operation less efficient. Finally, hot spots may persist as a result of any, or all, of the above conditions.
Concomitant with the ever increasing advancements in the volume and speed within which data is processed; data center operators are observing a rise in the energy of the thermal dissipation for the data processor equipment installed in upper plenum of the center. Indeed, the thermal dissipation energy, resulting with the use of such technologies, is now exceeding the operational design limitations, for even the most popular designs of air-grate floor panels in use today, in even those computer rooms which employ the lower-plenum/upper-plenum and hot aisle/cold aisle air separation boundary layer technologies. These uses generate enormous heat loads, on the system, for dissipation, within the same volumetric area, which significantly increases the concentration of heat applied to the internal data processing conductors in the server. For example, it is not uncommon to now experience server racks pushing 7 kw per rack, with operational expectations within the industry of scaling upwards to a 12-30 kw use. Thus, certain manufacturers of air-grate floor panels are experimenting with designs which further increase the available open area of the openings in the air-grate or perforations in the panel top plate. In addition, operators are also working on ways to lower the temperature set-point of the entire data center in order to enhance cooling of those computer servers which are positioned in the upper reaches of the server racks, in the upper plenum. However, the first design solution includes inherent structural load and safety limitations, and the second operational solution significantly drives up the cost in providing electrical utilities to the center.
Another structural solution is directed toward an effort in continuing to redesign the air flow characteristics of the air-grate panels themselves, with an appreciation in both the air flow separation dynamics, when passing through the flat bottom of the slotted air-grate, and also as to air flow passing through the air-grate when installed on a pedestal support system. One such design is illustrated in U.S. patent Ser. No. D567,398, to Meyer. There, it is ordinarily observed that air scoops are projecting downwardly as part of the superstructure of the air-grate frame. It is readily apparent that the scoop design would act to capture air, as it flows in a generally horizontal direction through the lower plenum of a raised floor. A fluid dynamic, inherent in such design, would result in an increase in the velocity of the air flowing from the lower plenum, as it curves upwardly when passing the scoop, and into the upper plenum, of a computer room, through slotted perforations in the air-grate floor panel plate. This increase in velocity would seem to enhance cooling and further promote the creation of air separation barriers within the computer room.
While the foregoing methods and materials are useful in providing thermal separation of the hot and cooling environments in a raised floor data center, there still exists a need to provide an improved air-grate floor panel and system which enhances cold aisle containment by generally ensuring that the cold air stays at the server intake, while the air handlers receive the warmer exhaust air, improving their efficiency. Moreover, there is a need for an improved structural design in the manufacture air-grate raised floor components which enhances the capture of warm exhaust air, via computer room air conditioners, conditions it, and returns it via the lower plenum through the cold aisle. Finally, there is a need to provide an improved air-grate structural design and system which effectively breaks the boundary layer of heat, in front of the computer server cabinets, and reduces the amount of bypass air, hot air recirculation, and hot air contamination, all of which would result in a reduction in the number of hot spots. The present invention satisfies these needs.